Need to justify the luxurious business sedan you just bought? Residual value should be near the top of your list. When buying a new car, depreciation and future resale financials are major factors, notes Kelley Blue Book market analyst Jack R. Nerad. "The average vehicle retains only about 35 percent [of its value] after a five-year ownership," Nerad says. "But some retain closer to 50 percent." Among those are high-end luxury models whose residuals after two years can approach 60 percent. For instance, the 2006 percentage for the Infiniti Q45, replaced this year by the M45, is 56 percent; for the Cadillac STS, it's 57 percent; and for the Lexus LS460, it's 60 percent.

Cadillac's $42,250 STS luxury sedan improves its On-Star navigation and assist-ance service on 2007 models by adding a live advisor who gives you turn-by-turn directions played through the stereo system. The STS has a new, hydramatic six-speed automatic transmission teamed with its 3.6-liter 254-horsepower engine. Trunk volume: 13.8 cubic feet.